At present, perhaps the most popular portable electronic device in the marketplace is the foldable cellular telephone, which generally includes a cover section and a body section. Typically, the cover section and the body section are rotatably interconnected through a hinge assembly, for switching the telephone between an open in-use position and a closed position.
One kind of hinge assembly employs a cam and a follower, to make the cover section open up from the body section and be held in an open position. An example of such kind of hinge assembly is disclosed in U.S. Pat. No. 6,292,980. The hinge assembly includes a cam having a concave portion, a shaft having a convex portion, and a spring which makes the concave portion tightly contact the convex portion. The cam, the shaft and the spring are received in a housing. A flip cover rotates about a main body of the mobile phone by overcoming the force of the spring, to make the concave portion rotate about the convex portion. However, a user must open the mobile phone using both hands. This makes the mobile phone awkward to utilize in situations when the user has only one hand free.
Therefore, a new hinge mechanism is desired in order to overcome the above-described shortcoming.